RIBBON-LIKE COMPRESSION FOSSILS FROM THE LATE EDIACARAN ESMERALDA MEMBER OF THE DEEP SPRING FORMATION AT MOUNT DUNFEE, NEVADA, USA

Abstract We describe > 200 ribbon-like macroscopic fossils from terminal Ediacaran strata at Mount Dunfee, Nevada, USA ∼ 115 m below the local placement of the Ediacaran–Cambrian boundary. They are preserved as casts and molds, composed of Fe-oxides and Fe-rich aluminosilicates in an aluminosilicate clay matrix. Measurements of 50 of the specimens provide a fossil size range of 0.22–0.74 mm-wide and 0.1–75.0 mm-long. Some specimens evidence original flexibility and appear to be fragmented, consistent with soft body preservation. They are therefore interpreted as body fossils, rather than trace fossils. Given this interpretation, we suggest that the fossils’ size range and ribbon-like morphologies are consistent with them being members of the problematicum Vendotaenia, which have not been previously reported from Ediacaran strata within the southern Great Basin. The phylogenetic affinity of vendotaenids is unresolved, but they are commonly interpreted as a form of eukaryotic macroalgae. This report firmly establishes vendotaenids in Ediacaran strata on Laurentia, broadening their known paleogeographic range during the end-Ediacaran Period. Additionally, the morphology of the fossils described here supports the notion that, although vendotaenids are reported from many Ediacaran paleocontinents globally, there was low macroalgal diversity at the end of the Ediacaran Period.